Method of refining lead for use thereof in antifriction alloys containing other metals which are not adapted to be alloyed with lead



June 20, 1933. E, D r AL 1,914,788

METHOD OF REFINING LEAD FOR USE THEREOF IN ANTIFRIGTION ALLOYS CONTAINING OTHER METALS WHICH ARE NOT ADAPTED TO BE ALLOYED WITH LEAD Filed Dec. 1929 Patented June 20, 1933- I UNITED STATES PATENT OFFICE ALFRED EDOUARD RICARD AND LOUIS DANIEIi, OF PARIS, CE

METHOD or nnrmme In son Usn THEREOF IN ANTIFBICTION ALLOYS (301mm.

JIN'G OTHER METALS WHICH ARE NOT ADAPTED TO BE ALLOYED WITH LEAD Application filed December 7,

The invention relates to a. method for the purification of lead used in the production of anti-friction alloys containing an antifriction element lead to which "are added,

5. eventually tin and antimony, and characterized by the fact that the lead undergoes, prior to its mixture with the other'metallic constituents, a treatment consisting in the introduction into the molten mass of lead or thelike, heated above its temperature of fusion and stirred up violently by mechanical means, of about 5%, by weight, of chlorinated alkaline salts, formed by a mixture of an alkaline chloride with an alkaline oxalate mixed with a substance capable of assuring its decomposition by reduction and accompanying reducing and desulphurizing actions.

After the treatment of the lead in the speci fied way the metallic components of the. alloy, such as bronze, brass or aluminium alloy, and

serving as support, are mixed in suitable proportions with lead, tin and antimony serving as the proper anti-friction element. The cblorinatedalkaline salts serving for the preliminary treatment of lead can be utilized either in a gaseous or in a liquid state. The main action of these alkaline chlorinated salts in liquid state is to serve as a molten body facilitating thJuttermost division and an in- 3 ,timate mixture of the anti-friction metal the supporting metal, whereas the main action of these bodies in their decomposition into a gaseous state is to act as a reducing agent in the mass of the alloy and at the exact moment of its formation; both of these actionscannot be readily distinguished under the usual material conditions. The chemical treatment alluded'to in the present invention facilitates an intimate and 40 homogeneous alloy of non-alloyable metals, such as of the anti-friction metal at one part, and of the supporting metal, at the other part,

at the very moment of the production of the alloy, the principal effectof this treatment being to facilitate later on, at the moment of the mechanical utilization of the parts constituting said alloy, and raised to a higher temperature owing to a high friction-speed or to a high pressure, the separ'ation of particles of the anti-friction metal and its exuda- The total quantity of these alkaline chlo- 1929, Serial No. 412,451, and in France December 29, 1928.

tion upon the friction surface, so as to form an adhering and fat pellicula affording a perfect insulation of the friction surfaces. This result has previously been sought for, particularly in friction bronzes with a 5 high proportion of lead, but hitherto the methods employed, whether by impeding the exudation of the lead or allowing it to be free in a state which does not permit the deposit to form, which separates the two friction surfaces and so prevents wear of the friction members, have been unsatisfactory.

The uttermost division of the anti-friction metal in the support of the alloy permits the latter to preserve, almost'without modi-- fications, the mechanical characteristic features which it possesses without any admixture.

An example of themanufacture of a special anti-friction metal or alloy, with copper, lead and tin as fundamental constituents, is given hereafter by way of example.

1. Preliminary treatment of Zead.A mixture of chlorinated alkaline salts is introduced into the heated lead, composed of an alkaline chloride such as sodium chloride NaCl, with ammonium oxalate C OANHQ H O or of the oxalate of potassium C O K +H O well mixed in equal proportions with a substance which will assume their dc composition by reduction and create a reducing and desulphurizing centre such as caustic potash KOH.

ride salts used is about 5% of the metal treated, but this quantity could be varied from 1 to 10% according to the purity of the initial metal. v 1

Many organic materials, of numerous substances which can be obtained commercially, are equally utilizable, according to a low price or easy supply.

The temperature of the fusion bath is raised .to- 550 to 600 C. to assure the almost complete decomposition of the salts employed.

A second addition of a. quantity of these chlorinated alkaline salts is now made of about 1% by we1ght,-and the lead this treated ioo is used, to make the alloy immediately or at the time the metal is cast into ingots, for use later as will be hereinafter described.

2. Constitution of the anti-friction alloy. The materials destined. for the final alloy. are mixed, for example, in the following uantities: Cu Pb 20%, Sn 10%.

he quantity of lead, or of anti-friction alloy Pb+ Sn can vary from 9 to 50% without it being necessary to take special precautions in casting.

Melting is done in the usual manner, making use of a direct flame furnace or a crucible furnace, avoiding carefully oxidation. Casting is carried out at the usual temperature employed for the tapping of bronzes or alloys of copper, containing a large quantity of lead, after having strongly stirred the heated alloy to make sure that it/is mechanically mixed. The tapping or casting is carried out without any other special precautions.

It is possible to render visible the pheno enon of exudation of the anti-friction meta from its support when using mechanically the pieces, owing to friction and the conse quent raising of the temperature, by micrographic tests. L

It is, for example,'possible to magnify 200 times a view or photo of a section of a bearing bush perpendicularly to the surface of friction and previous and posterior to the mechanical work of the'same. In Fig. 1, the anti-friction metal 1 is, previous to the mechanical utilization of the piece, suspended in the formof drops within the mass 2 of the support.

According to Fig. 2, which shows the piece after its mechanical utilization, the anti-friction metal moved, according to tests, toward the surface of the bush and'oocupies there a superficial zone a, forming there a thin and fat pellicula, whereas toward the centre of the piece, in the zone a, the anti-friction metal remains suspended in the shape of drops 1. In the intermediate zone 6, the drops are, as visible, deformed and tend toward the shape of lenses lentils Z.

What we claim, is:

1. The herein described method of refining lead for use thereof in antifriction alloys' containing other metals which are not adapted to be alloyed with lead and consisting in treating raw lead at a temperature of approximately600 C. with a mixture ofsodium chloride, potassium hydroxide and ammonium oxalate, the proportion of such mixture being substantially 5% by weight of the lead to be treated.

2. The herein described method of refining lead for use thereof in antifriction alloys containing other metals which are not adapted to be alloyed with lead and consisting in treating raw lead at a temperature of approximately 600 with a mixture of sodium chloride, potassium hydroxide and potased to be alloyed with lead and consisting in treating raw lead at a temperature of approximately 600 C. with a mixture of sodium chloride, potassium hydroxide and a material from the monium oxalate an potassium oxalate, the quantity of said mixture re resenting approximately 5% of the weig t of the lead to be treated.

4. The herein described method of refining lead for use thereof in antifriction alloys containing other metals'which are not adapted to be alloyed with lead and consisting in treating raw leadat a temperature of approximately 600 C. with a mixture of sodium chloride, potassium hydroxide and an alkali oxalate, the quantity of said mixture representing approximately 6% of the Weight of the lead to be treated.

In witness whereof they aflix their signatures.

LOUIS DANIEL. ALFRED EDOUARD RICARD.

group consisting of am- 

